A refining skill is where you will take an item either pre-finished or raw and refine the item into a greater produce.
Examples:
*You mine a piece of or *You smelt that ore into a piece of metal *You refine that piece of metal into a sword
*You gather a piece of wool *You weave this wool into cloth *You refine the cloth into a piece of clothing
*You gather ginko wood *You refine raw wood into a wooden weapon